The present invention relates to an arm structure.
An arm structure is known in which, with one end side thereof being a center, the other end side can be tilted around it, and a vertical position of a heavy object supported on the other end side can be changed by tilting, as illustrated in Japanese Unexamined Patent Application Publication No. JP 06-309915 A. In such an arm structure, a spring is provided to each joint of the arm structure so as to generate a force in an anti-tilting direction so that the heavy object is stopped at any vertical position.